Process for improving alcohol quality



Patented Dec. 22, 1953 i PROCESS 'FOR IMPROVING ALCOHOL I UALITY Samuel W. Wilson, Baton Rouge, La., assignor to Standard Oil Development Company, a corpo ration of Delaware No Drawing. Application December'13, 1950, Serial No. 200,687

This invention relates to the purification of alcohols and aqueous solutions thereof and particularly to the removal therefrom of malodorous impurities.

It is well known that the substantially watersoluble alcohols containing 1 to 5 carbon atoms per molecule and particularly those prepared by the acid-catalyzed hydration of mono-olefins are often contaminated with materials which give rise to distinct unpleasant odors which render the final product unsaleable or at least limit its marketability. The above is especially true of those alcohols prepared by the sulfuric acidcatalyzed hydration which process is presently in commercial operation in the preparation of ethanol and isopropanol from ethylene and propylene respectively.

employed is preferably one of not finer than 30 mesh particle size. Particle sizes above 30 mesh are operable but are not as satisfactory. Particle sizes of 4-20 mesh are preferred, although coarser material may be used. The finely divided glass requires no preliminary treatment prior to its use. Although the types of glass named have been found to be effective in removing malodorous materials from alcohols, other solid materials of a similar nature suchas silica gel, silicic acid, diatomaceous silica and asbestos produce no improvement whatsoever in the quality of the alcohol.

The odors associated with the alcohols, especially those prepared by the sulfuric acid-catalyzed hydration of mono-olefins are generally of two distinct types. The first has been called in the trade recycle odor. This odor is usually a light fugitive odor associated with low boiling sulfur compounds such as mercaptans, thio-aldehydes, etc. It is believed that these low boiling sulfur compounds result from .the decomposition of a higher boiling parent compound releasing the sulfur compound and in addition a hydrocarbon. Therefore, a hydrocarbon odor is usually always associated with the recycle odor. The second type of odor is termed butyl odor. Thisodor is a strong hydrocarbon-type odor attributed to the presence of the so-called high-boilers in the alcohol. The high-boilers include high boiling hydrocarbons, high boiling oxygenated compounds and high boiling sulfur compounds. It

9 Claims. (Cl. 260-643) The intimate contact of the impure alcohol with the finely divided glass is carried out with the alcohol either in the liquid phase or in the vapor phase. However, liquid phase treatment is preferred. In conducting the liquid phase contacting two methods are preferably employed, namely, gravity fiow of the alcohol through a bed of finely-divided glass, or upfiow passage of the liquid alcohol under pump pressure through the bed of finely-divided glass. However, it is also possible to mix the alcohol and the ground glass by agitation and thereafter separate the alcohol from the mixture by passage through a filter press, or by settling and decantation. However, this method is not preferred to the passage of the liquid alcohol through a bed of glass which may be more satisfactorily achievedin a continuous manner. If a vapor phase operation is desired the alcohol is heated above its boiling point and the vapors are percolated through a body of the glass.

In case of incomplete removal of the malodorous materials the rate of flow of the liquid through the glass may be decreased, the depth or the number of the beds may be increased, and/ or the passage of the alcohol through the bed may be repeated. The rate of flow through the bed can be fixed at a figure of 0.5 to 60.0 volumes or alcohol per volume of glass per hour. Generally a rate of 6-20 v./v./hr. is preferred.

The mechanism of the operation whereby the odor is removed is not known. However, it has been established that the glass not only removes the malodorous impurities from the alcohol but also removes reducing substances. Alcohols filtered through a bed of glass show a decided improvement in permanganate time which is a measure of the reducing substances present. Recycle odor may possibly be due to the presence of reducing substances. "But in addition the butyl odor of the alcohol is also improved and the materials giving rise to butyl odor are not necessarily reducing materials. The permanganate time employed in testing the treated alcohols is the USP method which is a measure of the time in minutes for 0.1 cc. of 0.1M solution of KMnO4 has been found that treatment of the alcohol with odor and in all cases diminishes the intensity of the butyl odor. On some occasions other odors such as acetate, menthol and peppermint odors are observed but these are not frequently found in the alcohols.

at 15 C. to fade from a light pink color. The lower the permanganate time in minutes the poorer the quality of the alcohol indicating the presence therein of reducing materials.

Up to the present time it has not been found necessary to carry out any regeneration of the glass since no harmfuleffect has been observed by continuous treatment of the alcohol with the glass. It has been found further that an extremely poor quality alcohol can be passed.

through the bed of glass and a decidedly improved alcohol recovered therefrom. Immediately thereafter a more defined, less .malodorous alcohol can be passed through the same bed and it too is upgraded in its quality, particularly its 7 odor. Itis contemplated that, when necessary,

the glass man be re 'v'lfieii by a simple operation such as aeration, washing with water, weak acid or weak alkali, or mere movement of the glass within the bed.

A total of approximately 1100 volumes of 'iso- ;5 propanol per volume of porous glass was passed ing Table II. through an experimental columnmontaining:ap- TABLE n proximately 18 cc. of fiHBIWdiViGGdQOI-Olls eglass at rates from 7 to 33 v./v./hr. without any indication that the glass is spent or that :anylosswf ,1 I r Rate Over Odor efficiency occurred at the higher rates. Results mngml'ethaml gg fiff ffluent of these experiments are reported in the .following Table I. The isopropanol was a product pre gecyc e an dry OdOI. 250 60 Norecyc1e.. pared by the sulfuric avoid-catalyzed hydration an fi l or L 60 Do. swam. 15 gait-Ha. TABLEq Rgggle-and-badvoliorflveryrpoori 25.0:- 60' ;D.0.. 1 m" 1 ovemenamzisopropanol y contacting I with Mycof porous glass -.(wWo:c. :mol. 1 aofggms) It has also .been found'that the shape and r v sharpness of.g1ass particles has vvno critical fifiegjb. .oddmmfigmal jslgilixllgos ltagigecil .oaomfmuent on theactivityoftheglass; Rough sharp :par- 1 l ticles andsmooth round granules bothgivereffeci tive results. 1%; g; 3g: 'It has been found that the JJOIOllSgEMfiSgmn- 3; g: 3%: ules-and crushed flint glass willupgrade ,any ag g: imalodorous alcoholqwhatsoeverrregardlessmfzthe .zg: state'of its re'finement. Even :ag0od:alcohol re- 50 "2' '11 acts favorably. *The-alcoholafterassed throu h T250; .45 1 250i the glassneeds no ,further .treatmehtan'giis sent directly .to storage. In-the tablesfifitting-foflh g g: the .zresult of experimental work, :alcohols :are 250 s 2S1.B. #900- R and E 35 graded as follows. ZIVIDOOI .'5 f 3112 mig g.

'gg Grade l.tAlcohol with no t foreign-o'dor. ggg g ggg Grade 2.,An alcohol .with .a .veryislight foreign 5-. f3 RMICLB odgn 333 25 E 3% 40 Grad "a An 1 i101 'th ill 4 an L e .F f ,1, 'I' 5 mm 5 :3E'and3 V a co w1 a moderately notice 2, 000 5 able odor. 9 p Grade -4.-'llnalcoho1 containingappreciam t mimymmdor (excessive-amounts. odor. .fi gyzl-gg aggomodor. g gfi fg fi" The, following tables show the efiectiveness ot g g i approximate compositim solid porous glasses in achieving the :removalsor g g pgg S diminishing of-various types of-odor from' isoljgig sjilfi propanol of different statesof refinement and lgfiggtg f gag of different initial odor ratings. Comparative s1 c, .fgmggscejgmomlmgefimi ens data showing :the anegative react ons 10f o her m or A gg gt figgigggi tmq.mar in. slhceous adscrbentsl are also tabulated.

'TABLEIII similar results were ea1so ohtained by contacting ethanol prepared by the sulfuric acid-catalyzed hydration of ethylene with granular Vycor" glass. These results are tabulated in the follow-- LEfiect of sozm .glass on removing recyle ..o.'dor

vfmm isopropanol 1 .Quanany of Alcohol'before Alcohol after 13mg x alcohol, contact cannot .Reniarks P orous fVycor glass.-- et -.18 600 4 rec. and'HC 3 HO, no rec. Definit j tovement Cnishdfiintglass. was 2,100 .do d0 P irPyr'eicglasehelices- 3-1: 1, 200 do gflc g LDCL i cat e irec. and HC Ngimprovement Acid; silicic (SiOfXHzO v 6 1500 do 13 iDicalite .(diatomaceous slime)" 6 x300v -do Activated alumina 6 l2 600 do Asbestos 300 -Qu1te sour-odor N improvement.

"'Rec:="recycle 111G=hydrncarbom minnow.odorimpartedJoalcohol.

1 TABLE IV Efi'e'ct ofsolz'd glass on removing recycle and hjj drocarbon odor from isopropanol than} Al hlbi Al h l ft ityo co 0 core 00 0 a er Packmg alcohol, contact qcontact R Porous Vycor glass 12-15 1,800 3 rec. and 110*". 2 E0, no rec Definite improvement. Crushed flint glass 12-15 1,80 do do Do.

lica gel 3-18 3 rec. and H0... No improvement. Acid silicic (SiOa-XHz0)- 6 d0 D0. Dicalite (diatomaceous silica 6 .-do Do. Activated alumina 6-12 do Do. Asbestos 6-18 Quite sour odor-No improvement.

Rec. =recyc1e.

HO =hydrocarbon.

"Very mild with respect to recycle; would be grade 3 HO without recycle present.

=new odor imparted to alcohol.

TABLE V Effect of solid glass on removing butyl odor from isopropanol Quan tit oi Alcohofbefore Alcohol alter Packmg alco l iol, contact contact Remarks gorogs gycori glass l, 388 4 bu gyl 3 b 1521 Defi ige improvement.

rus e intgass n Pyrex glass helices 3-16 1: 200 do 2 butyl Do. gorge g eL z 3-12 1, 300 "W3 4 gy No iggirovement.

Cl S1101 l 2 2 O Dicelite (diatomaceous silica) Do. Asbestos 6-18 Sour odor-Butyl odor, no improvement- -New odor imparted to alcohol.

Ihe following data demonstrate the effectiveness of glass granules in improving the permanganate time of malodorous ethanol prepared by the sulfuric acid-catalyzed hydration of ethylene:

The shape or form of the glass particles appears to have some effect on the effectiveness of the material in removing odor from the alcohol, for example, flint glass produces its best results in the form of crushed, irregularly-shaped, finely-divided particles. The same is true of the porous Vycor glass. On the other hand Pyrex glass shows best results when used in the form of glass helices. Less effective results are obtained in those instances where each of the glasses is employed in the form of glass wool.

What is claimed is:

1. A process for improving the odor characteristics of a water-soluble alcohol contaminated by high-boiling hydrocarbons and sulfur compounds which make the alcohol malodorous and which is prepared by hydration of a mono-olefin, which comprises intimately contacting the contaminated malodorous alcohol with finely-divided solid glass particles in the absence of other purifying agents at a space velocity in the range of 0.5 to 60 volumes of the alcohol per volume of the glass particles per hour, whereby the alcohol is rendered substantially less malodorous.

2. A process according to claim 1 in which a.

malodorous is passed up through the bed of the: glass particles.

3. A process according to claim 1 in which the malodorous alcohol is in vapor phase and inti-- mately contacted with the glass particles.

4. A process according to claim 1 in which the glass is ground flint glass.

5. A process according to claim 1 in which the glass is finely-divided porous glass.

6. A process according to claim 1 in which the glass is Pyrex glass helices.

7. A process for improving the odor characteristics of a water-soluble alcohol prepared by sulfuric acid-characterized hydration of an olefin, said alcohol being contaminated by dissolved organic sulfur and hydrocarbon odorless impurities, which comprises intimately contacting a stream of the malodorous alcohol in liquid phase with a bed of finely divided solid glass particles of 4 to 30 mesh particle size at a flow range of 0.5 to 60 volume of the alcohol per volume of the glass particles per hour in the absence of other purifying agents whereby the alcohol is rendered substantially less malodorous as it is passed through the bed.

8. A process according to claim 7 in which the malodorous alcohol is malodorous ethanol prepared by hydration of ethylene.

9. A process according to claim 7 in which the malodorous alcohol is malodorous isopropanol prepared by hydration of propylene.

SAMUEL W. WILSON. (References on following D 86) References Cited in he file of this patent UNITED STATES S Number Name rmu Measey --V-----,j f- 7 7 C3851151501 lDec. 23, 18 90 Bloom Nov. .30, 4915 Mann Dec.' 9,":1924 Johns July 20. 6 Pike t'dl. ;.3a.x 1.:1O, H 2B Jakob May*31,;2[35

-1unx ber N mbQI 7 8 Name Date Craig Sept. 14, 1937 "Be'r'guis 'e'tal Feb. 7, 1939 Bump Jan. 23, 1940 Lind w u -11 Mar. -1, 1949 -Nijboer Mar. 27. 1951 FOREIGN PATENTS Country Date H Germany Nov. 1,1897 -Gra2t Britain :Nbv. 19 15 

1. A PROCESS FOR IMPROVING THE ODOR CHARACTERISTICS OF A WATER-SOLUBLE ALCOHOL CONTAMINATED BY HIGH-BOILING HYDROCARBONS AND SULFUR COMPOUNDS WHICH MAKE THE ALCOHOL MALODOROUS AND WHICH IS PREPARED BY HYDRATION OF A MONO-OLEFIN, WHICH COMPRISES INTIMATELY CONTACTING THE CONTAMINATED MALODOROUS ALCOHOL WITH FINELY-DIVIDED SOLID GLASS PARTICLES IN THE ABSENCE OF OTHER PURIFYING AGENTS AT A SPACE VELOCITY IN THE RANGE OF 0.5 TO 60 VOLUMES OF THE ALCOHOL PER VOLUME OF THE GLASS PARTICLES PER HOUR, WHEREBY THE ALCOHOL IS RENDERED SUBSTANTIALLY LESS MALODOROUS. 